Computed Tomography Flashcards
7 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Computed Tomography flashcards as text
Which CT artifact is caused by two high-density objects lying in the same scan plane?
Answer: Beam hardening artifact
Beam hardening occurs when polychromatic X-rays are differentially absorbed, causing dark streaks between dense structures like metal implants or dense bone.
What does the term 'pitch' refer to in helical CT scanning?
Answer: The table distance traveled per gantry rotation divided by beam collimation
Pitch is calculated as table feed per rotation divided by total beam collimation width; a pitch of 1 means the table moves exactly one beam width per rotation.
Which window setting is most appropriate for evaluating pulmonary nodules?
Answer: Lung window (WW 1500, WL -600)
The lung window uses a wide window width and low window level to optimize contrast between air-filled lung parenchyma and soft tissue nodules.
What is the primary purpose of a bow-tie filter in a CT scanner?
Answer: To shape the X-ray beam and reduce dose to peripheral tissues
A bow-tie (wedge) filter is thicker at the edges to attenuate X-rays where the patient cross-section is thinner, reducing peripheral skin dose and detector saturation.
A patient with a creatinine level of 2.8 mg/dL is scheduled for contrast-enhanced CT. What is the most appropriate next step?
Answer: Consult with the ordering physician regarding contrast risk and alternatives
Elevated creatinine indicates reduced renal function and significant risk of contrast-induced nephropathy; the ordering physician must be consulted to weigh risk versus benefit.
Which reconstruction algorithm produces the sharpest bone detail in CT imaging?
Answer: High-frequency (edge-enhancing) kernel
High-frequency or bone kernels accentuate edge transitions, producing sharper images ideal for cortical bone and temporal bone detail, though they increase image noise.
What is the typical Hounsfield Unit (HU) value for simple (non-hemorrhagic) cerebrospinal fluid?
Answer: 0 HU
Simple CSF measures approximately 0–15 HU, close to the value of water, allowing differentiation from higher-density hemorrhage or proteinaceous fluid.